Engine shaft drive unit



- March 25, 1958 Filed March 8, 1954 O. P. PULLINS ENGINE SHAFT DRIVE UNIT 2 Sheets-Sheet l INVENTOR. dlPPl/ll/l/J' Filed March 8, 1954 March 25, 1958 o. P. PULLINS 2,827,799

) ENGINE SHAFT DRIVE UNIT 2 Sheets-Sheet 2 mullmvm INVENTORI 0.4 PULL/NJ United States atent ENGINE SHAFT DRIVE UNIT Owen P. Pullins, Chula Vista, Calif., assignor to Rohr Aircraft Corporation, Chula Vista, Calif., is corporation of California Application March 8, 1954, Serial No. 414,691

2 Claims. (Cl. 74-425) This invention relates to a machine for turning over an engine having a rotary shaft and for setting the shaft at a precise position.

Multicylinder engines,-especially those having six cylinders and more, offer considerable friction to rotation of their shafts, especially if the engine has been in storage for a period before being installed in an airplane or other vehicle. When large multicylinder engines are installed in aircraft, sometimes the magnetos are attached to the engine at the time of installation in the airplane and it becomes necessary to turn the engine shaft one or more revolutions to bring the driving part on the engine in registry with its mating driven part on the magneto. In other instances when the magneto is already attached to the engine, it is necessary to rotate the engine shaft after the assembly of the engine and its auxiliary equipment such as oil pump, fuel pump, etc. in the engine cowl to time the magneto or for other purposes. Since in most installations magneto distributors are gear driven and since it is usually necessary to rotate the timing mechanism both clockwise and counterclockwise to set the timing device, it becomes necessary to rotate the engine shaft one or more revolutions in either direction to take out the back lash of the gears prior to making the final timing adjustment. It is also necessary to rotate the engine shaft slowly in its normal operating direction to bring the timer to the position which assures correct timing of the spark at the spark plugs.

It is accordingly an object of my invention to provide a power drive capable of turning an engine shaft quickly in either direction to an approximate shaft position.

Another object is to provide such a power drive with means which permits its easy and quick connection with the end of the engine shaft and its ready disconnection therefrom.

A further object is to provide such a power drive with a member conveniently located for manual operation to effect the precise setting of the engine shaft.

Another object is to provide a support or frame for the power drive with attaching means which permit it to be easily attached to a depending cable of a hoist whereby the drive may be easily lowered into operating position and later removed from the engine.

Further objects will become apparent as the description of the drive unit proceeds. For a better understanding of the invention reference is made to the accompanying drawing, in which:

Fig. 1 is a perspective view, partly schematic, of the invention applied to a multicylinder airplane engine;

Fig. 2 is a perspective view of a power driveembodying the invention and;

Fig. 3 is a sectional view taken on line 33 of Fig. 2.

The drive unit comprises a flat base plate which has secured thereto at one end a vertical plate 11 to the top of which is secured a horizontal plate 12 terminating in a pair of projecting fingers 13, 14. The portion 15 of plate 12 between these fingers is semi-circular and :1

2,827,799 Patented Mar. 25, 1958 small clearance space 16 (Fig. 3) is provided between plate portion 15 and an annular hub 17 secured to the center of a worm gear 18. Secured to the inside of hub 17 is a brass bushing 19 Whose face is machined to provide a plurality of splines 20 which fit a set of mating splines 21 provided near the end of the engine shaft 22 to engage and drive the airplane propeller (not shown). Worm gear 13 is supported by a semi-circular band 23 which extends into a circular groove 24 in a circular ring 25 which is secured to the supporting web 26 of gear 18. Band 23 is in turn supported by three posts 27 (two being shown) which are secured to the band and to base plate 10. The drive unit is attached to the upper end of the engine frame or housing 28 by two or more bolts 29 which pass through holes in base 10 and engage threaded holes 30 in housing 28. In case the shaft 22 is equipped with a thrust collar 31 to take up axial thrust a circular recess 32 is cut in the lower face of plate it to receive collar 31.

To assist in supporting worm gear and maintain it in contact with its drive worm 33, a pair of semi-circular arms 34 are spaced apart by a plurality of spaces 35, three ball bearings 36 being mounted on pivots 37 passing through the arms. At one end the arms 34 are pivotally supported on pivot 38 and their opposite end may be secured to finger 14 by a securing pin 39 which passes through aligned holes in the arms and finger.

Worm 33 is secured to a shaft journaled in a vertical post 41 which is secured to plates in and 12, the rear end of shaft 40 being driven by a coupling 42 secured to the output shaft 43 of a reversible compressed air motor 44. The front end of shaft is provided with a hand wheel 45 for manual operation to set the engine shaft 22 to a precise position as later described. The top of post 41 carries a cross bar as which helps support compressed air supply pipes 47, 4-3 and has secured to it an eyebolt 49. Pipes 47, as are selectively supplied with compressed air by a valve control unit of known type having a pivoted actuating lever 51 having a handle 52 Compressed air is supplied to the unit through a rubber hose 53 from any suitable source (not shown) and when handle 52 is depressed it causes a pair of valve actuators 54 (one only being shown) to open a valve (not shown) which admits air into pipe 48, this air causing the rotation of shaft 43 and worm 33 in one direction. When handle 52 is raised, it causes a pair of valve actuators 55 to open a valve (not shown) which admits compressed air into pipe 47, thus causing the rotation of shaft 43 and worm 33 in the opposite direction. A second eyebolt 56 is secured to base plate 10 and a third eyebolt 57 to a disc 58 permanently secured to a band 59 which is attached to the edge of plate 10 by a plurality of screws (not shown). Plate 1% has slot 60 terminating in its front end to permit the endwise removal of worm gear 18, ring 25, hub 17 and bushing 18 as a unit after removal of band 59. If an engine having a different number or shape of splines 21 on its shaft is to be rotated, another similar worm gear unit is substituted but having a bushing 19, the splines 20 of which fit those on the engine shaft. By withdrawing the latch pin 39 and moving arms 34 about their pivot 33, it is clear that one worm gear unit may be withdrawn and another substituted instead.

Referring to Fig. 1 a multicylinder radial airplane engine 61 is shown partly schematically as being supported on a stand 62 with its shaft 22 vertical. The drive unit is suspended on a sling 63 attached to eyebolts 49, 56, 57, and engaged by a hook 6 attached to a cable 65 whose upper end is wound around a power driven winch 66 which may be rotated in either direction by an electric motor (not shown).

ice

To use the drive unit, winch 66 is operated to raise it above the engine and then reversed to lower it onto the engine, the operator guiding frame 10 so that the upper end of engine. shaft 22 enters the hole in bushing t19 and the splines it) slide down the splines 21, on'the 'engi'ne' shaft 7 Bolts 29 are then inserted and screwed into the threaded holes 30 thereby securing plate 10 fast to' the top of engine housing 28 as shown in Fig. 3'. The op t erator then operates handle 52 in a direction to cause air tion' is continued until the backlash of the reducing gears 67 is taken up (Fig. 1) which drive the magneto68 and.

until the piston 69 of number 1 cylinder reaches approximately the bottom of its stroke. This maybe determined in a known manner by removing its spark plug and iiiserting a Wire through the plug opening, allowing the end of the wire to rest on the top of the piston; Hand wheel 45 is then rotated by the operator to rotate the engine shaft further in its normal direction of rotation until piston 69 reaches the proper. position in the cylinder at which the magneto should fire the spark plug. 11f the magneto timer (not shown) is correctly adjusted, the drive unit may be removed from. the engine by loosening the bolts 29 and operating winch 66 to lift the unit; If the timer is not properly set, it is adjusted in a known manner while the piston remains in position, and the drive unit is then removed from the engine.

This invention may be embodied in other forms; or carried out in other ways without departing from the spirit or essential characteristics thereof. The present embodiment of the invention is therefore to be considered as in all respects-illustrative and not restrictive; the scope of the invention being indicated by the appended claims, and all changes which come within the meaning and" range of equivalency of the claims are intended to be embraced therein.

Having thus described my invention, what I claim as new and useful and desire to secure by Letters Patent is z" 7 1. Drive means for connection to the upper end of a s'aid motor; a worm wheel having a central opening adapt ed topass the upper end of said shaft; means attached rality of anti fri'ction' bearings; means tor locking said member to said frame to retain said anti fric'tidr1 hearings in contact with the periphery of said collar; and drive means connecting said collar to the upper endof the shaft.

2. Drive means for rotating an engine shaft protruding from the upper end of an engine housing and provided on one end thereof with a plurality of splines, comprising: a supporting frame; detachable means for attachting said supporting lfrarnze to the upper end of said engine housing; a reversible motormounted on said frame; said motor having an output shaft provided with a worm;

motor control means for selectively eausing said output shaftto rotate in either direction; a worm gear in mesh with said worm, said gear being provided with a central opening adapted to pass said engine shaft; a drive member 7 secured to the upper surfaceflof said gear" for rotation therewith, said member being provided with a plurality o f splines adapted to interfit with the splines on said engine shaft; means on said frame arranged to suppoir t said worm,

gear in mesh with said worm incliidiri'gha semi-circular collar comprising a pair of spaced apart arms having antifriction bearings disposed therebet'ween adapted to engage the outer surface of said drive member, onsend of'saidl collar being pivotally connected to saidfiranie and the.

other end being adapted to be locked to said frame; a circular ring secured to the lower-face of said gear;

and means on said frame in engagement with said ring to rotatably support said ring and worm'ge'ar.

References Cited in theme tuns patent UNITED STATES i A'r'nNr s Fredly Mar; 10, 1834' 938,807 Brewer Feb. 7, 1911 1,902,934 Acker Mar.- 28, 1933 1,983,007 Simons Dec. 4, 1934 2,089,934 Du'nham Aug; 17, 1937 2,313,548 Hoge Mar. 9, 1943 2,352,140 Tl'ofit June 20, 1944 2,391,418 Hodgson Dec. 25, 1945 2,513,643 7 Grimer July 4, I950 

